Ring current development

Chen, Margaret W.

doi:10.1016/b978-0-12-815571-4.00005-6

Cited by 3 publications

(2 citation statements)

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“…KHAZANOV AND CHEN 10.1029/2021JA029211 2 of 11 Like all precipitation, diffuse auroral electron precipitation which results from magnetospheric wave-electron interactions produces backscatter, alters the ionospheric conductance and affects inner magnetospheric electrodynamics. The electrodynamics potentially influences the formation of the plasmasphere (Huba & Krall, 2013), ring current (Chen, 2020;Chen, Lemon, Guild et al, 2015;Chen, Lemon, Orlova et al, 2015;Ebihara, 2016;Fok, 2020;Jordanova, 2020), and radiation belt seed population (Khazanov et al, 2004). A conceptual third step that involves a framework for using the diffuse precipitating electrons to calculate the inner magnetospheric electrodynamics, namely the self-consistent electric and magnetic fields that influence particle transport and loss including the primary precipitation is introduced and discussed in this paper.…”

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Why Atmospheric Backscatter Is Important in the Formation of Electron Precipitation in the Diffuse Aurora

Khazanov

Chen

2021

JGR Space Physics

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Magnetic storms and substorms result from a complex interaction of the solar wind with the Earth's magnetosphere. They reconfigure the near-Earth geospace environment and cause major increases in energetic particle precipitation in the auroral zone, making them an important component of space weather. The average integrated number flux of the precipitating auroral ions is typically 1 to 2 orders of magnitude less than that of the precipitating auroral electrons (Hardy et al., 1989) and precipitation of <∼30 keV electrons accounts for ∼80% of auroral energy into the ionosphere (Newell et al., 2009). Therefore, the flux formation of precipitating electrons is the focus in this paper.There are three main auroral electron precipitation mechanisms: wave scattering of plasma sheet electrons into the loss cone; sometimes called diffuse aurora, acceleration by interactions with Alfvén waves; broadband or Alfvén aurora, and acceleration due to a quasi-static parallel electric field; monoenergetic or discrete aurora. Distributions of diffuse auroral electron fluxes precipitating downward into the ionosphere are often well represented by Maxwellian, kappa or Gaussian distributions (e.g.

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Why Atmospheric Backscatter Is Important in the Formation of Electron Precipitation in the Diffuse Aurora

Khazanov

Chen

2021

JGR Space Physics

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“…Both the line current method and 1D SECS method assume that the FACs flow along radial lines of a uniform magnetic field between the ionosphere and the inner magnetosphere and, hence, FACs do not contribute to the magnetic field component parallel to the main magnetic field. This assumption is approximately valid in polar regions at quiet magnetic times, but it is rather violated at magnetically disturbed times when the earthward edge of the inner magnetosphere moves closer to the ionosphere up to geocentric distances of ∼ 3R e (e.g., Baumjohann and Treumann 1996;Daglis et al 1999;Tsyganenko 2013;Chen 2020) and the curvature of field lines of the main magnetic field becomes important (see Section "Estimation of the auroral oval locations"). In this paper, we will abandon the assumption of a uniform main magnetic field and consider FACs flowing along the field lines of the Earth's magnetic dipole, which is a more realistic FAC geometry valid up to geocentric distances of ∼ 8R e (e.g., Daglis et al 1999;Tsyganenko 2013).…”

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An electric circuit model of the Earth’s polar electrojets and field-aligned currents for the estimation of magnetospheric magnetic field from along-track Swarm magnetic data

Martinec

Velı́mský

2022

Preprint

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This study deals with the analysis of Swarm vector magnetic data in order to create a circuit model of electric currents flowing in the Earth's polar ionosphere and the inner magnetosphere. The model is composed of a system of two dimensional electric currents representing the magnetic fields of three-dimensional ionospheric polar electrojets (PEJs), the field-aligned currents (FACs), magnetospheric ring currents (MRCs) and magnetospherically induced electric currents inside the Earth (MICs) for each Swarm track. The aim of this paper is to model PEJ and FAC magnetic fields in terms of electric currents on a track-by-track base, subtract those magnetic fields from along-track Swarm magnetic data and estimate the magnetospheric magnetic field (MMF) in discrete time bins. The proposed method is primarily intended to apply to Swarm signals recorded during magnetic storms. The electric circuit model is set up in three steps. After subtracting the main, lithospheric, Sq ionospheric and oceanic tidal magnetic fields from along-track Swarm magnetic signals, the residuals are grouped in 1-h time bins and adjusted by the magnetic field of a two-circular loop model of MRCs and MICs represented by 3✖2 parameters of the electric circular loops in the magnetosphere and the Earth. The adjustment is carried out for the X and Z magnetic field components only because the Y component contains a large signal due to FACs. In the second step, the modelled MRC-MIC magnetic field is removed from the original residuals and the reduced residuals are adjusted by the magnetic field of a system of two-dimensional electric circuits in the polar ionosphere and FACs. The circuit model is set up according to known geometry of PEJs and FACs. In the final step, the modelled magnetic fields of PEJs and FACs are subtracted from the original residuals and all three magnetic field components are adjusted by the MRC-MIC model, named MMC, in a similar way as in the first step. Reliability of the approach is demonstrated by the scatter plots of model MMC showing a significantly better agreement with Swarm magnetic field residuals than the existing MMFs.

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An electric circuit model of the Earth’s polar electrojets and field-aligned currents for the estimation of magnetospheric magnetic field from along-track Swarm magnetic data

Martinec

Velı́mský

2022

Earth Planets Space

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This study deals with the analysis of Swarm vector magnetic data in order to create a circuit model of electric currents flowing in the Earth’s polar ionosphere and the inner magnetosphere. The model is composed of a system of two-dimensional electric currents representing the magnetic fields of three-dimensional ionospheric polar electrojets (PEJs), the field-aligned currents (FACs), magnetospheric ring currents (MRCs) and magnetospherically induced electric currents inside the Earth (MICs) for each Swarm track. The aim of this paper is to model PEJ and FAC magnetic fields in terms of electric currents on a track-by-track base, subtract those magnetic fields from along-track Swarm magnetic data and estimate the magnetospheric magnetic field (MMF) in discrete time bins. The proposed method is primarily intended to apply to Swarm signals recorded during magnetic storms. The electric circuit model is set up in three steps. After subtracting the main, lithospheric, Sq ionospheric and oceanic tidal magnetic fields from along-track Swarm magnetic signals, the residuals are grouped in 1-h time bins and adjusted by the magnetic field of a two-circular loop model of MRCs and MICs represented by $$3\times 2$$ 3 × 2 parameters of the electric circular loops in the magnetosphere and the Earth. The adjustment is carried out for the X and Z magnetic field components only because the Y component contains a large signal due to FACs. In the second step, the modelled MRC–MIC magnetic field is removed from the original residuals and the reduced residuals are adjusted by the magnetic field of a system of two-dimensional electric circuits in the polar ionosphere and FACs. The circuit model is set up according to known geometry of PEJs and FACs. In the final step, the modelled magnetic fields of PEJs and FACs are subtracted from the original residuals and all three magnetic field components are adjusted by the MRC–MIC model, named MMC, in a similar way as in the first step. Reliability of the approach is demonstrated by the scatter plots of model MMC showing a significantly better agreement with Swarm magnetic field residuals than the existing MMFs. Graphical Abstract

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Ring current development

Cited by 3 publications

References 83 publications

Why Atmospheric Backscatter Is Important in the Formation of Electron Precipitation in the Diffuse Aurora

Why Atmospheric Backscatter Is Important in the Formation of Electron Precipitation in the Diffuse Aurora

An electric circuit model of the Earth’s polar electrojets and field-aligned currents for the estimation of magnetospheric magnetic field from along-track Swarm magnetic data

An electric circuit model of the Earth’s polar electrojets and field-aligned currents for the estimation of magnetospheric magnetic field from along-track Swarm magnetic data

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